Add Rust release coverage versioning

[PLeVasseur]

Most likely involves adding functionality to extension which will:

Read both of the following from each guideline:

• options for :version_start: and :version_end: which each take a version e.g. 1.XX
• options :edition_start: and :edition_end: which each take an edition e.g. 2015

Nice to have:

• to format these in a way in the rendered text such that they each are a range, e.g. (1.XX, 1.YY)

Consider how to make maintenance reasonable when we support a new edition and version:

• script that can bump based on FLS changes?

Consider how we can align this with the FLS' scheme of releases

• need to learn more about this

Originates from unfinished discussion on #27